1. General Field
Our invention is in the field of fiber optics; and in particular relates to disconnectable connectors for optically coupling optical fibers to each other, or to light sources or detectors.
2. Prior Art
The conventional arrangement for coupling optic-fiber components to each other is illustrated as FIG. 2. A fiber 111 is cemented into a metal ferrule 112, and the cable sheathing 119 terminated in an enlarged portion of the central cavity of ferrule 112 or in any other convenient fashion. Held securely to ferrule 112, as by flange 113 and circlip 114, is connector shell 115, with internal threads 117.
These threads mate with external threads 123 of another fitting 122 that is attached to mating optical device 121--which may contain another fiber, or may be a source or detector. Of course when the threads are screwed together the outer diameter of ferrule 112 slides within the inner diameter of fitting 122. Precision machining is required at surfaces 116, 118, 126, 125, 124 and 112, to assure a smooth sliding fit, concentricity of the fiber-optic tip and the end of a mating fiber in device 121 (or in any case the end of cavity 124), and proper abutment of the fiber-optic tip 118 with the transmissive surface 127 of mating optical device 121. In particular, exceedingly careful control of the longitudinal distance between surfaces 116 and 118, and that between surfaces 126 and 125, is required to obtain reliably an actual contact between optic fiber 111 and mating surface 127, without excess pressure that could cause breakage or scratching if the connector shell 115 is screwed on too far.
While serving a useful purpose, such connectors have certain limitations. They require considerable time for connection and disconnection; and equipment design must leave ample "finger room" all around each connector for screwing and unscrewing--tending toward unduly bulky apparatus. The precision machining requirements also make these connectors relatively expensive.
Connectors offering quick-connect and quick-disconnect capabilities are common in another field--that of electronics. In that field such connectors have resolved the annoyances of time and equipment bulk analogous to those mentioned above for fiber-optic equipment, by providing push-pull connectors easily and quickly inserted and withdrawn with fingers placed on only two sides of the connector, without rotation. For example, a brochure published in August 1977 by Lemo U.S.A. Inc. of Berkeley, California illustrates a line of quick-connect/disconnect electrical couplings accommodating coaxial cable and multiconductor cables having up to 18 wires.
Another publication, one-page and undated, from the same company summarizes the same information as in the August 1977 brochure, and also mentions four other product lines: "high voltage connectors," "fiber optic connectors," "fluidic connectors," and "cable assemblies." None of these latter four product lines is illustrated or detailed, and actual inquiry with the firm reveals that it does not have "fiber optic connectors" available. If that firm did have such connectors they might well be of a screw type such as appearing in FIG. 2.
There are problems associated with fiber-optic connectors which do not arise in regard to electrical or electronic connectors, and to our knowledge no prior-art disclosure provides solutions to the particular problems of quick-release fiber-optic connectors. In the case of electrical connectors, such as those of Lemo U.S.A. Inc., the male pins on one half of the connector simply slide into the female pins on the other half of the connector, to whatever depth results from the positioning of the connector shell (whether quick-connect or not). There is no need to control the insertion depth accurately. But depth control is essential for fiber optics.